In　the　part　of　the　paper,　use　bentonite　as　a　basic　material　synthesis　with　phenolic　aldehyde　foam　plastic.　The　experiment　mainly　researched　into　the　capacity　of　the　synthesis　to　purify　and　store　rain　water.　The　results　show　that,　water　absorption　polymer　phenolic　aldehyde　foam＇s　addition　to　environmental　mineral　material　can　promote　the　capacity　of　purifying　rain　water　greatly,　with　10　percent　of　bentonite,　the　removal　of　BOD5　in　the　rain　water　can　be　promoted　to　90　percent,　COD＇s　to　80　percent,　during　which　the　removal　turbidity　can　be　83　percent.　While　use　bentonite　only,　the　removal　rate　of　BOD5　can　only　be　62　percent,　the　removal　rate　of　COD　can　be　20　percent,　and　the　removal　rate　of　turbidity　can　be　68　percent.　So　it　depends　on　the　local＇s　pollution　conditions　to　choose　environment　mineral　material　to　purify　the　rain　water　effectively.　When　choosing　bentonite　as　basic　material　to　synthesis　with　phenolic　aldehyde　foam　plastic,　the　polymer＇s　water　absorption　rate　and　rate　of　water　loss　to　rain　water　change　with　different　proportion　of　bentonite.　Through　the　purify　rain　water　test　with　plants　cultivated　in　environmental　mineral　material,　purify　layer　and　storage　layer　can　meet　all　the　requirements　including　the　function　of　purifying　and　storing　rain　water,　exhibit　benefit　of　the　synthesis　polymer.